Research on the Changes Characteristics of Air Quality and Influencing Factors in Xi'an during in Autumn and Winter
In order to study the change characteristics of ambient air quality and influencing factors in Xi'an during autumn and winter,emission reduction effect assessment and characteristic radar map were used to analyze the effects of traffic flow and meteorological conditions on ambient air quality.The results showed the concentrations of primary pollutants(PM10,SO2,NO2 and CO)in Xi'an decrease during stage Ⅱ of two study periods compared with the same period last year.However,the concentration of O3 increased compared with the same period last year and before control stage.Xi'an had 5 times PM2.5 heavy pollution periodsas a result of the local pollutants accumulation and secondary transformation in stage Ⅱ of two study periods.Firstly,the boundary layer decreased and most of the wind was still,which was not conducive to pollutants diffusion.Secondly,high humidity enhanced the hygroscopic growth of PM2.5.In addition,the increase of O3 concentration led to enhancement of atmospheric oxidation,and the formation capacity of secondary organic aerosol(SOA)became stronger.The traffic flow in Xi'an decreased 67%and 72%respectively in stage Ⅱ of two study periods,the concentration of NO2 in roadside stations and atmospheric air stations decreased by 30%to 50%.The on-road vehicle emission was the main direct source of NO2 in Xi'an.
control periodair qualitymeteorological factorsXi'an
万方数据
维普
